refridgerator compressor, wiring, function, air compressor

Thread Starter

ninjaman

Joined May 18, 2013
338
hello,
i recently got a compressor from a fridge and want to use it as an air compressor for airbrushing. i can not seem to find any info on this particular compressor or wiring diagram. i did find some information about the wiring. i can get it working but it seems to operate funny. i attached line and neutral and it came on. then i unplugged it, plugged it back in an got an ground hum. it made a slight humming noise. i am not sure what this is. i unplugged it for a minute, plugged back in and it worked. it seems to do this. as though there is some charge in the capacitor. it has a relay, i believe. and a small round object which i think is a starting capacitor. i am not sure what is going on with it. any help or advice would be great. thanks
simon
 

Chris65536

Joined Nov 11, 2019
270
It might be a startup delay. After a fridge has been running, the high side pressure is very high. If you shut it off and attempt to restart right away, the compressor may not be strong enough to start up against that back pressure, and will just burn out. The delay makes sure the pressure drops enough before letting the motor restart.
 

shortbus

Joined Sep 30, 2009
8,581
i recently got a compressor from a fridge and want to use it as an air compressor for airbrushing.
Does the paint you want to use work with refrigeration oil? Those compressors have oil in the crankcase that circulates with the freon and ends up back in the crankcase when used as they are made for. Your air output will include the oil when used as an air compressor. I don't know where on the planet you live but here in the USA you can get a small AIR compressor with the tank and both a pressure release and pressure sensor to control it for under $50 at Harbor Freight or most big box hardware stores.
 

Externet

Joined Nov 29, 2005
1,608
While a refrigeration compressor runs, the PTC starter is hot and its resistance very high. A very high resistance does not allow current to the starter winding and may hum as does not reach the needed torque to start/run.
Let cool for several minutes (10?) before restarting.

Wiring should be phase to C (common) and neutral (3) to M (main) or R (run)
The S (start) winding should be in series with the PTC to phase.

But there is several styles of starting circuits.

1612220910654.png
 

Reloadron

Joined Jan 15, 2015
5,934
You may want to give this a little more thought. Note the comments by shortbus above. People frequently want to use refrigeration compressors as basic compressors or even vacuum pumps. Refrigerant has oil added to lubricate the pump and this is by design. The mist of refrigerant oil just travels a loop like an automotive air conditioning compressor. Just go buy a pump for your intended application, they are not very expensive.

Ron
 
I did the R-12 automotive compressor for a vacuum pump for an R-12 system without problems except you had to power the 12V clutch. I was generally working on an R-12 car AC, so no problems there either with the oil.

or air-brushing, you basically want a diaphram pump.

For painting with a compressor that uses oil, you generally want a water separator and filter. For power tools, you want to add oil with a mister.

For vacuum pumps with oil, you need a filter on the discharge side.

You need to pay attention to see if the tool or valve can tolerate unlubricated air or it needs lubricated air.

I put together a bunch of manifolded 24 VAC ASCO valves that really annoyed me. They buzzed like crazy. Each one had to be ultrsonically cleaned and put back together so they would not buzz. I had about 60 of them to do,
 

#12

Joined Nov 30, 2010
18,222
A caution: Refrigeration compressors will develop more than 450 PSI if their output is confined. It is imperative that you control the maximum pressure!!!

(I never found out how much more than 450 PSI because I never had a container which would survive more than that.)
 

Thread Starter

ninjaman

Joined May 18, 2013
338
A caution: Refrigeration compressors will develop more than 450 PSI if their output is confined. It is imperative that you control the maximum pressure!!!

(I never found out how much more than 450 PSI because I never had a container which would survive more than that.)
Hello, thanks for the response and advice. money at the moment is not really there. i live in the uk so no harbour freight. the local equivalent selling air compressors that are big, loud and expensive. i have a helium tank and fire extinguisher, i want to use one of those as a tank. i dont want more than 45 psi for the airbrush as i usually only use 30 psi. 450 is way above what i want to use. the compressor has no fluid in it. i found it dumped and was empty, just dirty. not sure how long it will last without lubrication oil. i like the idea of making something and want to learn more about making my own air compressor. ebay will sell a controller for about £6 which includes the start/stop switch, regulator and release valve. i am going to look at those and find what may be suitable. so far the cost has been time picking up the compressor and getting it working and picking up two potential tanks. if it works it should be quite light weight and silent compared to a motorcycle in my room that weighs about 40kg.
 

Externet

Joined Nov 29, 2005
1,608
For 45 psi, even a spare tire works as reservoir.:rolleyes: Thinking of alternatives, I have in my basement behind spider webs, some sort of medical equipment meant to supply some respiration? air; matress inflation? ; perhaps you can find one at a junk place. Looks like a 15cm x 15cm x 10cm aquarium pump. Veeeery quiet.

Great to have your visit, #12. :)
 

jpanhalt

Joined Jan 18, 2008
11,088
@ninjaman,
I have done a little spray painting and airbrushing in my time. You don't need or want an oil-filled compressor (refrigerator compressors require oil). What you need is a low pressure, oilless compressor with low cfm capacity. They are cheap, and a used one is even cheaper. You may or may not need a dryer depending on where you live. A roll of toilet paper dryer is quite good for such low volumes.

1) We don't know what you are spraying. Urethanes are especially sensitive to contaminants like oil.
2) Water-based paints will also be sensitive to oil. Water-based paints can also be sensitive to water, but are less so.
3) You also need to consider a dryer based on where you live.

Have you really searched for such a compressor where you live? A modern sealed refrigerator compressor is probably the worst possible solution. Here's an ebay listing for £50: https://www.ebay.co.uk/itm/Air-comp...339124?hash=item3db537d0f4:g:R0sAAOSwSUBgFRLu

If you have anything equivalent to Craigslist (like local ads) you can probably get a good one for £20 or less. I am sure I could find one in the US for about $20.
 

shortbus

Joined Sep 30, 2009
8,581
Urethanes are especially sensitive to contaminants like oil.
That's why I asked him that in my first post. and it's not just urethanes most all automotive type paints will end up with "fish eyes" in the surface, since most refrigeration oils have silicone in them. Even with a real compressor setup stuff like Armor All and tire shine products used in a car can cause paint problems when repainting.
 

jpanhalt

Joined Jan 18, 2008
11,088
That's why I asked him that in my first post. and it's not just urethanes most all automotive type paints will end up with "fish eyes" in the surface, since most refrigeration oils have silicone in them. Even with a real compressor setup stuff like Armor All and tire shine products used in a car can cause paint problems when repainting.
I know from experience. No silicone, just ordinary contaminants. My first urethane job on a fiberglass model airplane looked horrible. Stripped and re-did it. I have had far fewer problems with catalysed DuPont Centari enamel, but I wonder whether it is still made.
 
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